Homework - Head Calculations

Solve the following problems using Excel or Google Sheets. Show all of your work and calculations.

1. A piezometer is placed in the ground at a site. The screen on the piezometer is at a depth of 172.7 ft. The elevation of the ground surface where the piezometer is located is 2193.0 ft above mean sea level. The pore pressure measured by the piezometer is 38.4 psi. Assume that sea level is the datum. At the location of the piezometer screen:

   a) What is the elevation head? [ft]

   b) What is the pressure head? [ft]

   c) What is the total head? [ft]

2. The following diagram represents a flow net describing seepage of water below a concrete coffer dam resting on a permeable soil which rests on impermeable bedrock. Recall that the the solid lines are flow lines and the dashed lines are equipotential lines. There is an equal amount of water through the flow channels defined by pairs of flow lines and the equipotential lines are contours of total head indicating head loss as water flows from the upstream side to the downstream side through the soil below the dam.

Assume:

H1 = 30 m
H2 = 8 m
D = 50 m
Ha = 22 m
Datum = Base of saturated soil (top of bedrock).

Calculate:

a) Total head at point A.
b) Elevation head at point A.
c) Pressure head at point A.
d) Pore pressure (kN/m2) at point A.

Submission

Save your work in a file named head_hw.xlsx and upload it on Learning Suite.

Grading Rubric

Total: 30 points

Criteria	Points
Problem 1a: Elevation head calculation	4
Problem 1b: Pressure head calculation	4
Problem 1c: Total head calculation	4
Problem 2a: Total head at point A	4
Problem 2b: Elevation head at point A	4
Problem 2c: Pressure head at point A	4
Problem 2d: Pore pressure at point A	4
Documentation and work shown clearly	2